Your velvia will be returned unmounted. (Although there are 4x5 projectors out there for a really impressive "slide show".) You should have no trouble getting prints made. The film will likely be drum scanned and printed on an ink-jet or RA-4 digital printer. (There are, of course, other types of scanners and printers as well as Ilfochrome.)
Dutch Elm disease was the talk of the town in Chicago when I was a little kid. They had to cut down an awful lot of them (Elm trees that is.<g>). Mostly Maple trees now.